PHYSICAL AND LITERARY. i^r 



compound of an acid and of the pure earth 

 of this rubftance j for the air which was at 

 firft attached to it, was expelled during the 

 diffolution. I then added thirty grains of 

 ftrong quick-lime in exceeding fine powder, 

 (hook the mixture W-cll, and filtrated it. The 

 powder remaining in the paper, after being 

 well wallied, was found to be a magnefia, 

 which, as I expeded, was deftitute of air j 

 for it was difiblved by the vitriolic acid with- 

 out effervefcence..; And the filtrated liquor- 

 contained the lime united to the acid ; for 

 upon dropping fpirit of vitriol into it, a white^' 

 powder was immediately formed. 



We muft therefore acknowledge a ftronger 

 attraction between the calcarious earths and 

 acids than between thefe and magnefia : but 

 how does it then happen, that, if magnefia 

 faturated with air be mixed with a compound 

 of acid and calcarious earth, thefe two laft, 

 which attraifl one another the moft firongly, 

 do not remain united ; but the acid is joined 

 to the magnefia, and the calcarious earth to 

 the air which it attrafts much more weakly, 

 than it does the acid ? Is it becaufe the fum 

 of the forces which tend to join the magnefia 

 fo the acid and the calcarious earth to the 



air 



